The present invention relates to fluorine-containing 3,6-di(3xe2x80x2,5xe2x80x2-bis(trifluoromethyl)benzene)pyromellitic dianhydride as a monomer which can be used in preparing polyimides with high glass transition temperature, low dielectric constant and excellent processability, and preparing method thereof.
Polyimide is widely used as film, resin, molded part, adhesive and insulator for electronic, automotive and aerospace applications due to its superior heat resistance, mechanical property and electric property.
Especially, its use is increasing for insulating layer of semiconductor chips in electronic industry due to its superior dielectric property and thermal/chemical stability. However, it still has a number of drawbacks to be solved for high performance electronic devices which are getting smaller and lighter. Therefore, the polyimide with low dielectric constant, high glass transition temperature and superior processability is needed to be prepared for integrated multi-layer chip applications.
According to the recent research works, polyimide synthesized from monomers containing fluorine, which has small van der Waals radius, large electro-negativity and high reactivity to other element, shows superior solubility, low water absorption and low dielectric constant. However, the introduction of fluorine substituent into polyimide also lowers the glass transition temperature. Accordingly, the synthesis of fluorine-containing monomer with rigid structure is required to obtain polyimide with low dielectric constant and high glass transition temperature.
3,6-di(3xe2x80x2,5xe2x80x2-bis(trifluoromethyl)benzene)pyromelliticdianhydride was prepared as a novel monomer by combining 3,5-bis(trifluoromethyl)benzene, which is a flucorine-containing benzene substituent, and pyromellitic dianhydride derivative having rigid backbone structure. Polyimide prepared from this monomer has high glass transition temperature, low dielectric constant, low water absorption and superior solubility. Therefore, its application can be expanded to electronic devices.